Disassembly and inspection of air separation centrifugal cryogenic liquid pumps

The general steps for disassembling, inspecting, and maintaining cryogenic liquid centrifugal pumps used in air separation (such as high-pressure oxygen pumps and medium-pressure nitrogen pumps) are as follows: 1. Preparation work: – Stop the pump from operating and cut off the power supply to ensure safety. - The low-temperature medium inside the pump is fully warmed up and purged to ensure no freezing occurs upon disassembly. - Confirm that the site environment meets safety requirements (in particular, ensure that the hyperbaric oxygen pump does not come into contact with oils or flammable materials). 2. Disassembly process: - Follow the equipment’s technical documentation to first remove the pipelines, valves, and connection screws ； - Remove the outlet and inlet connection flanges of the pump, and remove the gaskets ； - Remove the coupling and bearing housing assembly ； - Gradually disassemble the pump casing to inspect the internal condition, and remove the internal rotor, impeller, and guide vanes ； - Remove the mechanical seal or labyrinth seal components to check for wear. 3. Key inspection and measurement points: - Impeller wear, cavitation, mechanical deformation, and crack detection ； - Check the wear condition of bearing bushings and rolling bearings; measure the clearance if necessary ； - Surface inspection and dimensional measurement of rotor components, shaft sleeves, balance discs, and thrust discs ； - Verify the seals (mechanical seals or labyrinth seal rings) and check for any leakage points ； - Inspection of the cleanliness inside the pump casing and rotor channels to prevent blockage by impurities ； - Measure the runout of the pump shaft to determine its concentricity, and check for any signs of bending or vibration issues. 4. Repair procedures: – Replace worn or damaged parts, and strictly control the gaps during reassembly in accordance with the manufacturer’s requirements ； - All components are strictly degreased and deoiled (especially the hyperbaric oxygen pump) ； - Replace the gaskets and mechanical seal components again and assemble them. 5. Reassembly and debugging: – Install in reverse order to the disassembly sequence ； - Adjust axial play and radial runout to ensure critical tolerances ； - Adjust alignment and complete coupling alignment ； - Pump body sealing test (helium leak testing or other appropriate method) ； - Before being put into use, the oxygen pump must undergo strict degreasing treatment, and it can be used officially only after passing the explosion-proof and cleanliness inspections as required. 6. No-load and load-operating start-up tests: – During the first start-up, closely monitor operating parameters (flow rate, pressure, temperature, vibration) to ensure that the pump is operating properly and that the seals are reliable with no leaks ； - Make records after the debugging is complete for future reference. The above are general principles; specific maintenance should be carried out in accordance with the relevant equipment operation manuals and the manufacturer’s technical requirements. .